NEW MEXICO UNIV ALBUQUERQUE CENTER FOR HIGH TECHNOLOGY MATERIALS
Laser scatterometry is a technique which involves shining a light beam on an area to be characterized and measuring the angular distribution of the light that is scattered from that area. A laser is used so that the incident light will be monochromatic and coherent. It is also valuable, in many applications, to be able to confine the probe beam to a selected area, with a diameter of 10 um or more. The scattered light distribution is typically measured either by scanning a detector over an arc, using a fixed array of photodiodes that are mounted along an arc, or by measuring the scattered light intensity distribution at a hemispherical screen when sample symmetry requires more than a one dimensional distribution measurement. In most cases, a single line measurement along a 90 deg arc is sufficient, either because of sample symmetry or because of the ability to align the sample in the direction of interest. The wavelength of the light used is a determining factor in the range of feature sizes that will be measured. Thus, different wavelength sources are sometimes valuable. Also, the angle of incidence of the probing light beam is a factor in the range of features that will be characterized.
This article is from 'Advanced Processing and Characterization Technologies. Fabrication and Characterization of Semiconductor Optoelectronic Devices and Integrated Circuits Held in Clearwater, Florida on 8-10 May 1991. American Vacuum Society Series 10,'AD-A254 162, p54-55.